The Iowa caucuses are under way. Republican voters are making their choices in the nation's first presidential contest of 2012. And according to early entrance poll results, it appears two of the candidates are running strong - Mitt Romney and Ron Paul.

We'll hear more about that in a few moments. But first, we're going to check in with reporters at two caucus sites to see how things are going. First, NPR's David Schaper joins us from a Republican caucus site in Des Moines. David, tell us about the scene and about the turnout there.

DAVID SCHAPER, BYLINE: Well, Robert, I'm at the Polk County convention complex in downtown Des Moines. And there's a big crowd here. This is a really huge building. So there's just one small meeting room. And the line was out the door. In fact, they got started late because there are so many people still lined up, waiting to register. I'm told about 150 people are in this room and they are now going through the speeches of each of the candidates' representatives. I think they're about ready to wrap those up and will be passing out the paper ballots for people to mark their choices.

Interesting, as people, you know, got up to speak for the candidates, starting alphabetically, there was no one for Michele Bachmann, but when it came time for Ron Paul's turn, two or three people tried to jump up and speak on his behalf, as opposed to just the one anointed by the campaign to speak. And a young Texan who was very, very nervous to be here came and spoke on behalf of Rick Perry.

SIEGEL: And, David, you've been following the Newt Gingrich campaign for the past few days. You heard his closing argument to voters earlier today. He's lost some ground in the polls in recent weeks. How did he make his case today?

SCHAPER: Well, he tried to hit back at his - his main opponent that sees, that's Mitt Romney, the former Massachusetts governor. He's been really teed up, Newt Gingrich has, in the television ads, negative ads have been just fast and furious. By one count, 45 percent of the ads on television in the state of Iowa this campaign season have been negative ads attacking Newt Gingrich. And he waited a long time to respond to these attacks and has just been doing so lately. Today, even agreeing with a questioner who asked him if he thought Mitt Romney was a liar in his positions as - his position as a conservative. So, it's heating up, but he's down and we don't know yet if he'll bounce back.